Replace mic key with search in a11y keyboard.

BUG=339196

Review URL: https://codereview.chromium.org/143153005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247983 0039d316-1c4b-4281-b951-d872f2087c98

ui/keyboard/resources/layouts/system-qwerty.html

@@ -26,7 +26,8 @@
           hintTexts="{}|"></kb-key-sequence>
     </kb-row>
     <kb-row>
-      <kb-key class="microphone dark" char="Microphone" weight="150"></kb-key>
+      <kb-key class="search dark" char="Search" image='search' weight="150">
+      </kb-key>
       <kb-key-sequence keys="ASDFGHJKL"></kb-key-sequence>
       <kb-key-sequence invert=true keys=";&apos;" hintTexts=':"'>
       </kb-key-sequence>
@@ -77,7 +78,8 @@
       <kb-key-sequence keys="[]\" hintTexts="{}|"></kb-key-sequence>
     </kb-row>
     <kb-row>
-      <kb-key class="microphone dark" char="Microphone" weight="150"></kb-key>
+      <kb-key class="search dark" char="Search" image='search' weight="150">
+      </kb-key>
       <kb-key-sequence keys="asdfghjkl"></kb-key-sequence>
       <kb-key-sequence keys=";&apos;" hintTexts=':"'></kb-key-sequence>
       <kb-key class="dark" char="&#x000A;" align="right"